Digester



April e 1926.

J. W. VAN ALSTYNE DIGESTER Filed Oct. 5. 1925 ,--lllli JLU r l I /f 1 l l l l l i I l I 1 i l l i l l l 1 I l s 1 1 ,J f l I, Jr 1 i i I l l 1 l lower end of a Patented Apr. 6, 1926.

UNITED STATES JOHN' W. VAN ALSTYNE, 0F VANCOUVER, WASHINGTON.

pioneras.

Application led October 8, 1925. Serial No. 60,328..

To all whom t may concern:

Be it hereby known that l, JOHN W. VAN ALSTYNE, a citizen of the United States, and a resident of Vancouver, in the county of Clarke and State of Washington, have iiivented a new and useful Digester, of which the following is a specification.

This invention relates generally to the paper industry, and particularly to digesters such as are employed for preparing pulp by the sulfite process.

The first 'object of this invention is to prevent the accumulation of lime at the bottom of the digester and in the attached discharge fitting.

The second object is to prevent the stopage of the outlet at the bottom of the digester by the accumulation of lime, which sto page would cause a great loss, in time an material and reduce the capacity of the digester.

The third object is to improve the quality of the pulp prepared by admitting steam to the digester in a manner that a circulation of pulp and cooking acid will be set up and continued y, there thus insuring a ainst separation of lime rom the cook and a o against discoloration in the form of blotches and s ots which appearl in the finished aper, ue to improper mixing and undesirahle reactions set u b over-heating in the discharge tting, w ic condition is prevalent in the'present type of digester.

The fourth ob ect is to so construct the digester that eac and every cook can be completely discharged from the digester, thereby improving-.the quality of the pulp and increasing the capacity of a iven size of digester, besides eliminating t e losses arising from clogged outlet fittings.

These, and other objects, will become more apparent from the specification following as illustrated in the accompanying drawing, inwhichz The figure in the drawing illustrates the typical form of digester in vertical section showing the present side inlet for steam, in dottod lines, which inlet is not necessary with my arrangement. The main discharge valve and other well known parts and details are omitted. Only enough of the digester is shown to completely illustrate the invention.

Referring in detail to the drawing, there is illustrated the usual Banged rin 10 on whose horizontal portion is mounte a ring thoroughly 11 to which is secured the usual di ester shell 12,` which is lined with fire bric 13, for which the sleeve 14 on the ring -10 forms a footing. On the under side of the ring 1() is attached an outlet ordischarge fitting 15 to which is attached the flange 16 of the usual cutoff' valve (not shown).

The usual side steam inlet 17, whose vposition is indicated in dotted lines, is not employed, but is merely capped over if present on the digester. The bottom steam inlet 18 does not open directly into the fitting 15 but is provided with a vertical pipe extension 19, which projects well up into the digester, as shown, and discharges near'the footing of the sloping sides of the bottom cone of the digester. In other words-the pipe 19 discharges entirely above the fitting 15 instead of into the bottom of same, as is ordinarily the case.

The operation of the digester is similar to those in common use, but it is found in practice that very desirable results are ob-i tained thereby. First the steam is applied at a point withinthe digester where a circulation is set up which constantly agitates the entire contents 20 of the digester, causn ing the pulp and cooking acid to remain in mixed state and preventing the of these elements from each other the lime ingredient, which, being a perfectly separation and from heavy, discharge fitting if a proper circulation was not maintained. If this lime is permitted to settle within the discharge fitting 15 and steam is admitted only to the bottom of this fitting, naturally the concentrated heat will tend to'bake the lime deposit within the fitting until thewdischarge of the digester is completely sto ped.

Furthmore, i the digester cannot be cleansed after thedischarge of its pulp that which remains is not improved by repeated processing, and if any portion of the reprocessed pulp finds its wayout in a later batch, it will not add to the qualit of the pa er formed therefrom, but wil rather ten to produce a lower grade of paper.

l am aware that in some instances m has been admitted well up on the side of the digester. rThis, however, able since it tends to agitate the pulp near thegtop of the charge but permits the remainder to lie undisturbed within the digester,

during which'time the heavier lime naturally would naturally be deposited in the is also undesirglravitates toward and accumulates in the lscharge fitting. The greatest objection, however, resides in the fact that the cooking acid does not come in uniform contact with all of the wood, as should be the case.

I claim:

l. A digester for making sulfite pulp having, in combination, a containerfor pulp, said container havin a conical bottom formed thereunder; a finged elbow attached to said conical bottom; and a vertical steam inlet pipe passing through the outer side of said conical portion of the container.

2. A digester for making sulfite pulp consisting of a container for said pulp havin a conical bottom formed therein; having a ischarge fitting at the lower end of said conical bottom; and a steam inlet pipe projecting upwardly through said fitting and discharging near the lower end of said conical bottom above said fitting.

3. In a digester, the combination of a brick-lined container having a flanged conical bottom with a flanged outlet elbow attached to the bottom of said container flange; said outlet. having a side outlet formed on the bottom thereof for admitting live steam; and :i pipe extension in said bottom outlet terminating at its upper end near the bottom line ofthe container cone and adapted to deliver steam to the cook within said container without overheating the contents of the outlet fittings by maintaining a thorough circulation of the contents of the di ester.

JON W. VAN ALSTYNE. 

